systemd.md

SystemD

Generate a graph of boot process

systemd-analyze plot > boot.svg

Clean journald logs

Delete older then N days:

journalctl --vacuum-time=2d

Delete everything older then the last N bytes:

journalctl --vacuum-size=500M

System limits

The mappings of systemd limits to ulimit

Directive        ulimit equivalent     Unit
LimitCPU=        ulimit -t             Seconds      
LimitFSIZE=      ulimit -f             Bytes
LimitDATA=       ulimit -d             Bytes
LimitSTACK=      ulimit -s             Bytes
LimitCORE=       ulimit -c             Bytes
LimitRSS=        ulimit -m             Bytes
LimitNOFILE=     ulimit -n             Number of File Descriptors 
LimitAS=         ulimit -v             Bytes
LimitNPROC=      ulimit -u             Number of Processes 
LimitMEMLOCK=    ulimit -l             Bytes
LimitLOCKS=      ulimit -x             Number of Locks 
LimitSIGPENDING= ulimit -i             Number of Queued Signals 
LimitMSGQUEUE=   ulimit -q             Bytes
LimitNICE=       ulimit -e             Nice Level 
LimitRTPRIO=     ulimit -r             Realtime Priority  
LimitRTTIME=     No equivalent

If a ulimit is set to unlimited set it to infinity in the systemd config:

• ulimit -c unlimited is the same as LimitCORE=infinity
• ulimit -v unlimited is the same as LimitAS=infinity
• ulimit -m unlimited is the same as LimitRSS=infinity